title: Elastomeric microparticles for acoustic mediated bioseparations.
abstract: BACKGROUND
  Acoustophoresis has been utilized successfully in applications including cell trapping, focusing, and purification. One current limitation of acoustophoresis for cell sorting is the reliance on the inherent physical properties of cells (e.g., compressibility, density) instead of selecting cells based upon biologically relevant surface-presenting antigens. Introducing an acoustophoretic cell sorting approach that allows biochemical specificity may overcome this limitation, thus advancing the value of acoustophoresis approaches for both the basic research and clinical fields.
  
  
  RESULTS
  The results presented herein demonstrate the ability for negative acoustic contrast particles (NACPs) to specifically capture and transport positive acoustic contrast particles (PACPs) to the antinode of an ultrasound standing wave. Emulsification and post curing of pre-polymers, either polydimethylsiloxane (PDMS) or polyvinylmethylsiloxane (PVMS), within aqueous surfactant solution results in the formation of stable NACPs that focus onto pressure antinodes. We used either photochemical reactions with biotin-tetrafluorophenyl azide (biotin-TFPA) or end-functionalization of Pluronic F108 surfactant to biofunctionalize NACPs. These biotinylated NACPs bind specifically to streptavidin polystyrene microparticles (as cell surrogates) and transport them to the pressure antinode within an acoustofluidic chip.
  
  
  CONCLUSIONS
  To the best of our knowledge, this is the first demonstration of using NACPs as carriers for transport of PACPs in an ultrasound standing wave. By using different silicones (i.e., PDMS, PVMS) and curing chemistries, we demonstrate versatility of silicone materials for NACPs and advance the understanding of useful approaches for preparing NACPs. This bioseparation scheme holds potential for applications requiring rapid, continuous separations such as sorting and analysis of cells and biomolecules.
authors.affiliation: Department of Biomedical Engineering, Duke University, 101 Science Drive, 3361 CIEMAS, Durham, NC 27708, USA.
authors.forename: Leah M
authors.initials: LM
authors.lastname: Johnson
authors.forename: Lu
authors.initials: L
authors.lastname: Gao
authors.forename: C Wyatt
authors.initials: CW
authors.lastname: Shields IV
authors.forename: Margret
authors.initials: M
authors.lastname: Smith
authors.forename: Kirill
authors.initials: K
authors.lastname: Efimenko
authors.forename: Kevin
authors.initials: K
authors.lastname: Cushing
authors.forename: Jan
authors.initials: J
authors.lastname: Genzer
authors.forename: Gabriel P
authors.initials: GP
authors.lastname: López
mesh_terms: D000162:Acoustics; D001386:Azides / Q000737:chemistry; D002469:Cell Separation / Q000379:methods*; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D020724:Elastomers; D005374:Filtration; D005453:Fluorescence; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D012828:Silicones / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D019809:Streptavidin / Q000378:metabolism
chemical_list: D001386:Azides; D004129:Dimethylpolysiloxanes; D020724:Elastomers; D011108:Polymers; D012828:Silicones; D012833:Siloxanes; C036925:elastomeric polymer; D019809:Streptavidin